数列an的前n项和为sn,an=2/3sn+2/3n,求an+1是等比数列

数列an的前n项和为sn,an=2/3sn+2/3n,求an+1是等比数列 已知数列an的前n项和为sn,且sn+an=n^2+3n+5/2,证明数列{an-n}是等比数列 数列{an}的前n项和为Sn,Sn=2an-3n(n∈N)（1）证明数列an+3是等比数列,（2）求数列an的通项公式 等比数列an的前n项和为sn,sn=1+3an,求：an 已知数列{An},Sn是其前n项和,且满足3An=2Sn+n,n为正整数,求证数列{An+1/2}为等比数列 数列{an}前n项和为Sn,且an+Sn=-2n-1 证明{an+2}是等比数列 数列An的前n项和为Sn,已知A1=1,An+1=Sn*(n+2)/n,证明数列Sn/n是等比数列 数列｛an}的前n项和为Sn=2an+3,则an是等比数列 数列{an}前n项和为Sn,且2Sn+1=3an,求an及Sn 数列前n项和为sn,a1=1,an+sn是公差为2的等差数列,求an-2是等比数列,并求sn 已知数列{an}a1=2前n项和为Sn 且满足Sn Sn-1=3an 求数列{an}的通项公式an 设数列的前an的前n项和为Sn,Sn=2an-2^n(1)求a1,a2,a3(2)证明｛an+1-2an｝是等比数列（3